How did that happen

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[This posting has been removed]

You've answered your own question: in the case the fail-safe is incorrectly set and goes to full power on switch-on.

I 'm aware of a situation where the Rx had lost the fail-safe settings for no reason.

I too am a member of the "Tx on Rx on and Rx off Tx off " brigade.

Isn't this discussion missing the basic point - any model with its flight battery connected is potentially hazardous.

There can be no exceptions to this - neither transmitter on or off first is going to be 100% safe and we can argue the merits of either principle until the cows come home to graze on the patch. You may say that all your models' throttles operate in the same direction but this won't necessarily protect you when you switch on with an IC model selected that goes the opposite way to your ESCs or are helping a beginner. The only real failsafe is in your care and forethought - every electronic or physical precaution is simply an additional layer to protect against failure to handle the model safely.

What you must do is discipline yourself that while you take any additional precautions, you must handle the model as if you believe it can go to full throttle at any time - whether connecting the battery, carrying it to/from the strip or approaching it to retrieve it. For example, I always either taxi past myself or turn the model nose away before removing it from the flying area. If you need to go out onto the runway/field to retrieve a model, always approach it from behind whether you are in control of your transmitter or not.

What does the BMFA handbook say?

They aren't completely conclusive...

"(b) Pay particular attention to using the correct sequence appropriate to your model. For 35 MHz this is usually ‘get the peg, Tx on, Rx on’. For 2.4 GHz, you should be aware of any local transmitter usage limitations and if a flight peg is required, it must be obtained before the usual Tx on, Rx on sequence. Note that some radio equipment and occasionally a specific model set up, require that the Rx be switched on first. If this is so take extra care."

...and...

"(a)  Receiver OFF then transmitter OFF (Unless your equipment manufacturer specifies otherwise)."

I always set my failsafe as the first thing on any new model, especially one an electric motor. Using OpenTX I set the failsafe on the PC first before transferring the model to the TX (all my setups are template based now and always have a sticky throttle cut, so that will be in place from the first moment). I then then bind the RX with nothing but a spare servo in the throttle channel and test it; once I'm happy the throttle cut and failsafe works as it should the RX can go in the model and the rest of the setup can be done (without a prop for brand new models).

I do still do "TX on, RX on, RX off, TX off" myself, but it's more from habit these days. Given I religiously follow the process above to ensure my models have the correct failsafe from day 1 I could probably change to Steve's procedure without any safety problems - I can see some benefits to working that way. However, given I still have a few models on 35 and this is a 30+ year habit tI suspect I'll be doing it that way forever more!

Edited By MattyB on 26/11/2020 17:00:16